Skirts for vehicles propelled on air cushions



y 1970 R. H. LANDRY 3,511,331

' SKIRTS FOR VEHICLES PROPELLED ON AIR CUSHIONS Filed July 25. 19s?United States Patent O 3,511,331 SKIRTS FOR VEHICLES PROPELLED ON AIRCUSHIONS Roger H. Landry, Asnieres, France, assignor to Pneumatiques,Caoutchouc Manufacture et Plastiques Kleber-Colombes (SocieteKleber-Colombes), Paris, France Filed July 25, 1967, Ser. No. 655,940Claims priority, applic jiiglglzFrauce, July 25, 1966,

Int. 01. 1s60v 1/16 US. Cl. 180-127 Claims ABSTRACT OF THE DISCLOSUREBACKGROUND OF THE INVENTION In ground-propelled vehicles which \move asa result of being supported by cushions of air, either one or severalskirts guide the air jets which emanate from the orifice of the blowerand/ or blowers to the surface over which the vehicle travels. Thepresent invention relates to the design and construction of theseskirts. More particularly, the present invention concerns theorientation of the flexible elements which are used to make the skirts.

Skirts 'for vehicles propelled on air cushions must have the followingproperties and concurrently must satisfy the following requirements: (a)they must be light in weight and yet adapted to withstand any exteriorinfluences, for example, that due to tension, stress, environmentalconditions, etc., (b) they must be flexible in order to adjust withoutdifliculty to the obstacles which may be present or which may beproduced on the surface of the ground (c) the walls of the skirt shouldnevertheless be sufiiciently strong and possess a sort of spring actionso that they will return to their original position close to the surfaceof the ground as soon as the obstacle has been cleared by the vehicleand (d) they must substantially preserve their geometric shape for theentire period of time they are utilized.

It has been attempted to make these skirts from woven fabrics coatedwith an elastomer. However, irrespective of the textile material used,this method has not produced good results, particularly with skirtshaving the shape of a truncated cone with the smallest base positionedtoward the surface of the ground. It appears that the poor results aredue to the fact that the filaments of the skirt which cross each otherat right angles, do not produce the same angle with respect to thedirection of the stresses to which they are subjected.

SUMMARY OF THE INVENTION An object of the present invention is to avoidthe prior art disadvantages in skirts for vehicles which are displacedon cushions of air.

Another object of the present invention is to provide skirts forvehicles displaced on cushions of air which are light in weight and yetadapted to withstand exterior influences.

A further object of the present invention is to provide skirts forvehicles displaced on cushions of air which are 3,511,331 Patented May12, 1970 flexible, strong, and possess a sort of spring action whichreturns them to their original position close to the surface of theground after the obstacle has been traversed by the vehicle.

Other objects and :further scope of applicability of the presentinvention will become apparent from the detailed description givenhereinafter; it should be understood, however, that the detaileddescription and specific examples, while indicating preferredembodiments of the invention, are given by way of illustration only,since various changes and modifications within the spirit and scope ofthe invention will become apparent to those skilled in the art from thisdetailed description.

Pursuant to the present invention, it has been found that theabovementioned disadvantages may be eliminated and a much improved skirtfor vehicles being displaced on cushions of air can be obtained byproviding skirts which comprise an inner framework containing sheetscovered on the sides thereof with an elastomeric layer or coating. Theinner framework is made of flexible elements which are separated fromeach other and disposed in the direction of the stresses or thecomponents of the stresses to which the skirt is subjected duringoperation of the vehicle, in such a manner that as many as possible ofthese flexible elements operate under the same conditions.

According to the present invention, the framework generally comprises atleast two superimposed sheets or layers of flexible elements which arenot woven and are substantially inextensible, or show little tendencytherefor. The flexible elements of one sheet or layer are substantiallydisposed as described hereinabo-ve, that is in the direction of some ofthe stresses, while the elements of the other sheet or layer aredisposed in the direction of the other stresses to which the skirt isexposed.

According to a preferred embodiment of the present invention, theflexible elements constituting each layer or sheet are made from fibershaving a limited amount of elongation, for example, glass fibers orrayon fibers. It has been observed that this feature makes it possibleto obtain skirts which are light and flexible and virtuallynondeformable, and which have a high mechanical strength while at thesame time displaying the kind of spring action which is necessary topermit them to return to their original position as soon as the obstaclehas been traversed by the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS;

The present invention will become fully understood from the detaileddescription hereinbelow and the accompanying drawings which are given byway of illustration only and thus are not li-mitative of the presentinvention and wherein,

FIG. 1 illustrates a skirt as proposed by the present invention;

FIG. 2 illustrates another type of skirt according tothe presentinvention;

FIG. 3 illustrates a further type of skirt according to the presentinvention;

FIG. 4 illustrates the alignment of the filaments of one layer or sheetin another skirt according to the present invention;

FIG. 5 illustrates a different alignment of the filaments according toanother embodiment of the present invention;

FIGS. 6 and 7 illustrate an improved arrangement imparting to the skirtsa greater degree of elasticity; and

FIG. 8 illustrates a skirt with multiple lobes enclosing or surroundingsmaller skirts.

3 DESCRIPTION OF THE PREFERRED EMBODIMENTS In all of the embodimentsshown, the skirts have the shape of truncated cones. However, it is tobe understood that the present invention is also applicable to any otherdesired shape of the skirts.

FIGS. 1 and 2 are directed to embodiments wherein the skirts have theshape of straight truncated cones, whereas FIGS. 3, 4 and 5 refer toembodiments of the present invention wherein the skirts have the shapeof oblique truncated cones. All of the skirts are composed of aframework covered with an elastomeric coating or layer on both sidesthereof. The framework for the skirt shown in FIG. 1 comprises twosuperimposed sheets or layers of fibers, for example, glass fibers. Theflexible elements of one sheet or layer are arranged according tocircles which are substantially parallel to the bases of the truncatedcone, that is, in the direction of lines 1 of FIG. 1. The flexibleelement of the other sheet or layer of the framework are arrangedaccording to the generatraces in the direction of lines 2 of FIG. 1.Taken very schematically, the flexible elements disposed in thedirection of lines 1 resist the lateral stresses which are due to thepressure at the inside of the skirt, Whereas those disposed in thedirection of lines 2 resist the stresses directed downwardly andresulting from the surface difference between the two bases. Thus,according to the present invention, the flexible elements of the frameare oriented in the direction of the stresses to which they are commonlysubjected.

If the skirt shown in FIG. 1 is made from a conventional woven fabriccoated with an elastomer, the frame would be composed of the filamentsof the fabric which intersect each other at right angles and which havea uniform spacing with respect to each other. This would not have beensignificant with respect to the sheet having flexible elements orientedas circles parallel to the bases of the truncated cone. However, theother sheet would not have flexible elements oriented according to thegeneratrices. Accordingly, the skirt has a lower mechanical resistantand substantial deformations are produced when the skirt is used.

A skirt such as the one shown in FIG. 1, that is, in the form of atruncated cone, can be produced in the following manner. A layer of anelastomeric material, for example, rubber or an analogous material, isapplied to one sheet of the framework which forms concentric circulararcs and which when shaped as a skirt forms concentric circlessubstantially parallel to the bases of the truncated cone. A new layerof elastomer is applied to the coated sheet of framework and upon thislayer is placed another sheet of framework according to the radii of thecircular arcs of the first sheet, that is, in the finished skirt theflexible elements of the sheet are disposed according to thegeneratrices. A new layer of elastomer is then placed upon this latterframework and the composite is thereafter vulcanized. The skirt is thenmade by shaping the composite into a desired shape, for example, atruncated cone. In this regard, it should be apparent that if theflexible elements disposed according to the generatrices (line 2) wereextended, they would intersect at the apex of the truncated cone. It isequally possible to shape the truncated cone first and then vulcanizethe elastomer. The vulcanizing operation may be dispensed with it,instead of utilizing rubber, either selfvulcanizable materials orsynthetic materials are employed.

Although vulcanizing the framework has in itself the effect of limitingits elongation, it is generally desirable to use flexible elements whichare as inextensible as possible. Flexible elements which are resistantto elongation and which can be used to produce the framework of theskirt according to the present invention include glass fibers, forexample, fiberglass, metal fibers and any of the natural or syntheticmaterials which are also resistant to elongation. The natural fibersinclude those of animal or vegetable origin, for example, cotton, wool,silk, natural cellulose, etc., and the synthetic fibers may compriserayon, regenerated cellulose, saponified acetate fibers, nylon 6obtained by the condensation of caprolactam, nylon 66 obtained by thecondensation of hexamethylenediamine with adipic acid, saran obtained bythe polymerization of vinyl compounds, for example, vinylidene chlorideor copolymers thereof with other unsaturated monomers, protein fibers,for example, Vicara obtained from corn protein, Acrilan which is asynthetic fiber made from acrylonitrile, Dacron which is a syntheticpolyester fiber made from methyl terephthalate and ethylene glycol.Dynel which is a copolymer of vinyl chloride and acrylonitrile, Orlon,which is a synthetic fiber made from acrylonitrile, Vinyon HH which is asynthetic fiber made from a copolymer of vinyl acetate and vinylchloride, and other like materials. The preferred fibers are glassfibers or rayon fibers.

The elastomeric material used for coating the framework can include anyof the vulcanizable materials, for example, rubber or analogousmaterials and also selfvulcanizable materials as well as certainsynthetic materials, for example, synthetic resins which are light inweight and possess the properties of elasticity, flexibility, andsuflicient strength to absorb the stresses and forces encountered intraversing the terrain. Suitable materials include polyolefins, e.g.,polyethylene, polypropylene, etc., polyesters, e.g., polyethyleneterephthalate, etc., polyvinyl materials, e.g., polyvinyl chloride,polyvinyl acetate, etc., acrylate resins, e.g., polymethylmethacrylate,phenolic resins, e.g., phenol formaldehyde resins, urea formaldehyderesins, etc., polyurethane resins, and copolymers of these materialswith one another or with ethylenically unsaturated monomers, and similartype polymers. The flexible elements of the present invention may be inthe form of filaments, strands, cables, bands, etc. As has beenindicated hereinabove, it is advantageous to use glass filaments with aslight torsion or rayon having a slight elongation in conjunction withthe elastomeric material in forming the skirts of the present invention.

The framework of the skirt illustrated in FIG. 2 is similar to thatshown in FIG. 1. However, the skirt according to FIG. 2 is made byplacing a layer of elastomer, for example, rubber, upon a mold andwinding thereon a continuous filament or band which, being positioned inthe direction of line 3, constitutes in the framework the sheet or napwhich resists the transverse stresses. It will be noted that in thisconstruction, the flexible elements of this sheet or nap of theframework do not form true circles parallel to the bases. However, theangle which they form with the bases is sutficiently slight that theyoperate under the same conditions as the flexible elements of the skirtof FIG. 1 positioned according to lines 1. Upon the sheet or nap of theframe thus made, is placed a layer of rubber and positioned on thiscomposite is a second sheet of framework whose flexible elements aredirected according to the generatrices (line 4). Thereafter, a new layerof rubber is applied and the skirt which has thus been manufactured in amold is vulcanized.

The skirt shown in FIG. 3 has the shape of a truncated cone beingoblique and not having an axis of symmetry. As in the case of the skirtillustrated in FIG. 1, the framework is made up of two superimposedsheets or naps, the flexible elements of one of these sheets having theform of circles being substantially parallel to the bases (line 5), andthe flexible elements of the other sheet being disposed according to thegeneratrices (line 6). This skirt may be manufactured in the same manneras that shown in FIG. 1, and, as is the case with the skirt shown inFIG. 1. if the flexible elements disposed according to the generatrices(line 6) were extended, they would intersect at the apex of the obliquetruncated cone shown in FIG. 3.

It is also possible to make the framework of a skirt having the shape ofan oblique truncated cone by proceeding as in the case of the skirtaccording to FIG. 2. In the skirt having the shape of an obliquetruncated cone, the stresses due to the lateral forces to which theflexible elements of the framework are subjected are not, by reason ofthe variation in the. inclination of the walls, the same inall of thepoints of the circles parallel to the bases. On the same generatrix, thestresses also vary by reason of the variation of the diameter of thesections. Lines 7 of FIG. 4 represent lines which adjoin the pointswhere these stresses are the same.

According to the present invention, it is possible in the case of skirtshaving the shape of an oblique truncated cone to orient the flexibleelements of the framework, which are designed to resist the lateralforces or stresses, in the direction of these lines. This renders itpossible not only to cause these flexible elements to operate under thebest possible conditions, but also to make the skirt lighter byproviding at the different parts of the framework only the resistancewhich is necessary to absorb the forces or stresses to which they areexposed.

It is possible to use for this purpose flexible elements which aredifferent by their very nature and/or constitution. It is also possibleto utilize the flexible elements by varying the spacing therebetween,the flexible elements being arranged more closely or more tightly inzones where the forces or stresses are higher than in the zones wherethe forces or stresses are smaller.

In the modified embodiment illustrated in FIG. 5, the directions of thereinforcing flexible elements 8 and 9 correspond to those of thecomponents of the stresses. The angles of intersection of the elementsare variable in the downward direction of the skirt. Even while having anon-deformable wall which is in conformity with and follows the geometryof the theoretical outline of the skirt, it may be desirable to providea certain elasticity in the skirt to facilitate the passage of obstaclesand to compensate for instantaneous and abnormal stresses or forces.This may be achieved by making the skirt from several panels, such as11, connected with each other by means of an elastic joint which mayhave a shearing operation, for example, as shown in FIGS. 6 and 7.

In the embodiments described hereinabove, the framework of the skirts ismade from two sheets or naps. It is obvious that more than two suchsheets or naps could be provided without departing from the spirit andscope of the present invention. This is particularly the case if asingle sheet or nap does not provide suflicient resistance to thestresses or forces to which the skirt is subjected. Generally speaking,the present invention is not limited to the embodiments shown anddescribed herein. More particularly, it may be applied in other forms orshapes of skirts, and FIG. 8 shows by way of example the applicationthereof to a skirt 12 having multiple lobes surrounding or enclosingsmaller skirts 13.

Since modifications of this invention will be apparent to those skilledin the art, it is not desired to limit the invention to the exactconstitution shown and described. Accordingly, all suitablemodifications and equivalents may be resorted to which fall within thescope of the invention.

I claim:

1. A skirt for vehicles propelled and supported on at least onepressurized air cushion, said skirt comprising at least two sheetsseparated from each other by an elastomeric layer, each sheet formed byflexible elements separated from each other and the flexible elements ofeach of said sheets having a direction oriented to resist orthogonallyrelated groups of forces, the flexible elements in each of said sheetsbeing interconnected by the elastomeric layer which separates saidsheets, the flexible elements of said sheets being disposed in thedirection to resist said forces to which said skirt is subjected to bysaid pressurized air cushion, the flexible elements of one of saidsheets being disposed in the direction to resist one of said group oforthogonally related forces while the flexible elements of the other ofsaid sheets are disposed in a direction to resist the other orthogonallyrelated forces.

2. The skirt of claim 1 in the form of a truncated cone, wherein theflexible elements of one sheet are disposed according to thegeneratrices of said cone and the flexible elements of the other sheetare continuous filaments which form a helix with respect to the bases ofsaid cone.

3. The skirt of claim 1, in the form of an oblique truncated cone one ofsaid orthogonally groups of forces being transverse stresses theflexible elements of one sheet being disposed according to the linesadjoining the points where said transverse stresses substantiallyparallel to the bases are identical, and the flexible elements of thesecond sheet being disposed according to the generatrices of said cone.

4. The skirt of claim 3, wherein the flexible elements which aredisposed to resist said transverse stresses are arranged more closelytogether in zones where the stresses are higher than in zones where thestresses are smaller, thus providing at the different parts of the skirtonly that resistance which is necessary to absorb the force or stressesto which they are exposed.

5. The skirt of claim 3, wherein each of said sheets comprises at leasttwo partially overlapping panels interconnected by means of a flexiblejoint between the overlapping portions of said panels.

6. A skirt in the form of a truncated cone, for vehicles propelled onair cushions which comprises at least two sheets separated from eachother by an elastomeric layer, each sheet being formed by flexibleelements separated from each other and having a direction oriented toresist specific forces and stresses, the flexible elements of saidsheets being interconnected by the elastomeric layer which separatessaid sheets, the flexible elements of one sheet being disposed accordingto the generatrices of said truncated cone while the flexible elementsof the other sheet are disposed substantially parallel to the bases ofthe cone.

7. The skirt of claim 6, wherein the flexible element is a filamentwhich possesses a limited amount of elongation selected from the groupconsisting of glass fibers, metallic fibers, natural fibers andsynthetic fibers.

8. The skirt of claim 7, wherein the synthetic fiber is rayon.

9. The skirt of claim 6, wherein the elastomeric layer is selected fromthe group consisting of a vulcanizable rubber, a self-vulcanizablematerial or a synthetic resin.

10. The skirt of claim 6, wherein each of said sheets comprises at leasttwo partially overlapping panels interconnected by means of a flexiblejoint between the overlapping portions of said panels.

References Cited UNITED STATES PATENTS 2,151,307 3/1939 Smith 156-172 X2,377,650 6/1945 Reimel 161-144 X 2,698,032 12/1954 Bacon 161-144 X3,211,246 10/ 1965 Lewis 1 -127 3,254,731 6/1966 Schreiber -1273,339,655 9/1967 Guienne 180-127 3,388,766 6/1968 Bertin 180-127 A.HARRY LEVY, Primary Examiner U.S. Cl. X.R.

